ADLINK cPCI-9116 - Manual (Page 28)

18
• Signal Connections
User Common Mode (U_CMMD)
To measure ground-referenced signal sources, which are connected to the
same ground point, you can connect the signals in a User-Common-Mode
(U_CMMD) configuration. Fig 7 illustrates the connections. The signal local
ground reference is connected to the negative input of the instrumentation
Amplifier, and the common-mode ground potential to signal ground. The
instrumentation amplifier will now reject the 9116 series ground.
AIn
U_CMMD
n = 0, ...,63
Ground-
Referenced
Signal Source
Instrumentation
Amplifier
To A/D
Converter
Input Multipexer
V1 V2
+
-
+
-
V
cm
Common-
mode noise &
Ground
potential
Figure 7: Ground-referenced source and User Common Mode connections
3.3 Digital I/O Connection
The 9116 series card provides 8 digital input and 8 digital output channels. The
digital I/O signals are fully TTL/DTL compatible. The details of the digital I/O
signal specification can be found in section 1.3.
Digital Input(DI)
74LS244
From TTL Signal
To TTL Devices
Digital Output(DO)
Digital GND(DGND)
74LS244
Figure 8: Digital I/O Connection